The invention relates to devices for adjusting a seat in height and in inclination.
It relates more particularly to the cases where the seats in question comprise a base frame adapted to be fixed to the floor of the vehicle, possibly by means of a slide allowing longitudinal adjustment, and a sitting-portion frame mounted on this base frame by means of two separate mechanisms disposed one in front and the other at the rear of the seat and both operable by the person sitting in this seat, each of these mechanisms being arranged so as to allow adjustment of the vertical distance between one point of the base frame and a point of the sitting-portion frame, then to maintain this distance constant after adjustment.
The invention has especially as its aim to make the mechanisms in question such that they are simpler than those known at present, more robust than these latter, that they allow continuous adjustments and that they lend themselves to electric controls.
Each of the mechanisms of the kind in question in accordance with the invention is essentially characterized in that it comprises, on each side of the seat:
two horizontal bearing surfaces spaced vertically apart by a distance D and provided on one of the two frames (base and sitting portion), the upper bearing surface being orientated downwards and the lower bearing surface upwards,
a horizontal shaft vertically connected to the other frame and pivotably mounted thereon,
two flat Archimedes-spiral cams with identical ratios, but in opposite directions, interlocked angularly together and with the shaft so that the distance between two parallel planes applied respectively in opposite directions against two areas of these two cams is equal to D and remains so during rotation of these cams with respect to these planes, said cams being disposed vertically between the two bearing surfaces so that each of them is slidingly engaged with one of these bearing surfaces,
and a member operable by the person seated to control at will the rotations of the shaft in one or other direction.
These rotations of the shaft of the front or rear mechanism considered result in modifying the height of this shaft with respect to the bearing surfaces of this mechanism, so the height of the sitting-portion frame with respect to the base frame, and in short, the height of the seat immediately above said mechanism.
In preferred embodiments, recourse is had further to one and/or the other of the following arrangements:
the slope of the straight lines corresponding to the developed curve of each Archimedes spiral is of the order of 7.degree.,
the effective area of each cam extends over an angle of 360.degree.,
in an adjusting device in accordance with the two preceding paragraphs, the height of adjustment of each mechanism is of the order of 30 mm, which corresponds to a cam radius increasing from about 15 to about 45 mm and to a distance D of the order of 60 mm,
the shafts of the two mechanisms extend transversely with respect to the seat, the shaft of one of the two mechanisms is jointingly overlapped by an aperture with vertical parallel edges provided in the frame to which this shaft is not vertically connected, and the shaft of the other mechanism is mounted so as to be able to move slightly in the longitudinal direction of the seat,
the two bearing surfaces are provided on the base frame, which comprises two longitudinal angle-irons having a vertical flange and a horizontal flange, the upper bearing surface of each mechanism is a lug integral with the vertical flange of such an angle-iron, and its lower bearing surface is the stepped edge of a slot provided in the horizontal flange of said angle-iron and adapted to let pass portions of the two cams,
the shafts of the two mechanisms are connected to an electric unit operable by the person seated and allowing the six following manoeuvres at will: driving the first shaft alone in one or the other direction, driving the two shafts simultaneously in one and the other direction, and driving the second shaft alone in one and the other direction,
in an adjusting device in accordance with the preceding paragraph, means are provided for automatically interrupting the operation of the two mechanisms when, with any one of the controls being brought into use, one of these two mechanisms reaches its end-of-travel stop,
in a device in accordance with at least the paragraph which precedes the preceding one, means are provided for giving priority to the simultaneous controls of the two shafts over the other four controls,
in an adjusting device in accordance with the preceding paragraph, the electric unit comprises: a DC source, two small electric motors, and three control change-over switches, i.e. a first change-over switch mounted so as to connect the source to the first motor in one direction or in the other through the mobile contacts of two de-energized relays, a second change-over switch mounted so as to connect the source to the second motor in one direction or in the other through the mobile contacts of two other de-energized relays, and a third change-over switch mounted so as to connect the source in one direction or in the other simultaneously, on the one hand to the four relays and, on the other hand, to the two motors through the mobile contacts of these four relays then energized,
in an adjusting device in accordance with the preceding paragraph, the change-over switches are aligned from rear to front with the side of the seat and each carries an upwardly or downwardly directed arrow corresponding to the control provided by pressing this arrow.
The invention comprises, apart from these principal arrangements, certain other arrangements which are preferably used at the same time and which will be more explicitly discussed hereafter.